Underreamer.



C. BRYSON.

UNDERBEAMER.

APPLICATION FILE!) JUNE 29. I915.

Patented May 16, 1916.

WITNESSES enemas 11. season, or rrrr'snonen, rnnnsrnvnnra UNDERREAMER.

meaeso. specification of Letters n {Patented May is, rare. Application filed June 29, 1915. Serial No. 36,937. v

To all whom it mam/concern Be it known that 1, CHARLES R. BRYSON, a citizen of the UnitedStates, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Underrearners, of which improvement the following 1s a specification. I 0

My invention relates to improvements 1n under reamers.

The objects of my invention are toproduce 'a device adapted to enlarge the diameter of the drill hole-or well below the casing, without the necessity of withdrawing the casing, which device is simple 1n construction and operationwhile at the same time possessing great strength and durability to meet the requirements of deep well under reaming. These objects I accomplish by means of the device hereinafter more specifically described, reference belng had to theaccompanying drawings, forming part hereof, in which Figure l is a side elevation partly broken away to show the operative parts, the cutters being in operative posltlon. Fig. 2 1s a side elevation partly broken away, showing the device in position to be lowered into the well. Figs. 3 and 4 are details of the spring supporting plug. Fig. 5 is a fragmentary view of cutter and spring, showing spring plug on upper end of cutter. Fig. 6 is a plan View of the devlce. Fig. 7 is a section on the line 77 of, Fig. l.

- Referring to said drawings, 1, is the bit shank, which is formed by forging in the usual-manner, and is provided with a suitable recess or opening a for the reception of the cutters, 2, and socket 1), extending from said recess a, for the enlarged upper end of the weighted shank 3, and for the spring 4, the upper end of which is secured in the top of said recess and the lower end thereof to the top of said shank 3. The lower edges of the bit shank against which the upper edges of the cutters engage are tapered correspondingly with the upper edges of said cutters, in order to furnish a bearing or support for the cutters on the downward stroke of the under rearner. The bit shank is also provided with screw threaded openings 5,. for the reception of the correspondingly threaded spring plugs 6, which hold the cutter springs in operative position.

The cutters 2 are preferably formed of tool steel as shown, and are pivotally supported in the bit shank by the pins 7 The upper ends 8 of the cutters are angularly shaped to conform to the lower squaredsides 9 of the weighted shank 3. The upper squared portion 10 of the weighted shank is of larger cross section than the lower squared portion and is preferably slightly tapered. A ring or collar 11 isformed at the top of the weighted shank to prevent said shank from being pulled enti'rely between the cutters.v A spring 12 is interposed between each of the cutters and the side of the bit shank, and is adapted to force the cutters into operative: position when the knob or weight 13 of the shank 3,

drill hole or well below the casing, the ordi nary drill bit is removed from the string of drilling tools and the under reamer substituted, the parts are adjusted to the position shown in Fig. 2 by inwardly compressing the lower ends of the cutters and thus collapsing the same, then by pulling the shank 3 downward until the end of the upper portion of the weighted shank en-' gages the inner sides of the upper portion of the'cutters, the springs 12 are held compressed, thus holding the cutters in the posi tion shown in Fig. 2. The drilling tools with the under reamer attached are then lowered into the well, and when the knob of the weighted shank strikes the bottom of the well, the said shank is forced upward into the opening in the bit shank, the spring 4 holding said shank suspended contracts and the cutter springs force the upper ends of the cutters to their seat against the lower squared sides of the weighted shank and the cutters are then in position to ream the well below the casing. The under reameris then operated in the-usual manner and the diameter of the well is enlarged as desired and to the depth required.

The string of tools and attached under reamer may be readily withdrawn from the well when desired as the engagement of the sides of the cutters against the casing will tion for reaming the well as soon as they reach the end of the casing.

I claim as my invention and desire to secure by Letters Patent:

1. In an underreamer, the combination of a bit shank having a recess in its lower. end,

a plurality of cutters 'pivotally mounted in said recess, the upper ends of said cutters having vertically disposed recesses therein, a Weighted shank movably seated in said recesses and adapted when in lowered position to hold the cutters in inoperative position, and yielding means adapted to throw the cutters into operative position when said shank-is moved upwardly.

2. In an under reamer, the combination of a bit shank havinga recess in its lower in said recess and yielding means to hold the upper ends of said cutters in contact with said Weighted shank.

3. In an underreamer the combination of a bit shank screw threaded at its upper end, the said shank having a recess in its lower end, a socket extending from said recess longitudinally of said'recess, a plurality of cut-' ters pivotally mounted in said recess, the upperiends thereof forming a squared opening, a Weighted shank movably supported in said socket and seated inthe squared opening of said cutters, and yielding means to hold the cutters in contact with said weighted shank.

In testimony whereof, .I have hereunto signed my name in the presence of two subscribing witnesses.

CHARLES 11.. BRYSON.

In the presence of JAMES C. HERRON, CLARENCE A. WILLIAMS- Y 

